Investigators returned Monday to a house where they found two sets of human remains, one identified as a girl missing for several months, and brought in heavy equipment to help search for more evidence.
A body found in a shed behind the rented home of Ward Weaver on Saturday was identified as that of 13-year-old Miranda Gaddis, one of the two teenagers who vanished last winter from an apartment complex down the road from Weaver's home.
On Monday, a medical examiner began examining the second corpse found by investigators Sunday in a barrel buried under a concrete behind the house — to determine whether it is that of 13-year-old Ashley Pond, the other missing teen.
The FBI refused to say how agents knew to look in the shed and beneath the slab for bodies.
"That's not something I'll comment on," Beth Anne Steele, spokeswoman for the FBI, said at a Monday news conference.
Both girls vanished from an apartment complex just down the road from Weaver's home.
"Obviously, this is a very sad conclusion to this investigation," said Charles Mathews, the FBI's special agent in charge in Oregon. "On the other hand, I think the case has been resolved."
Using pick-axes and a back-hoe, investigators dug into a corner of Weaver's backyard on Monday in the search for more evidence.
Asked whether more bodies could be buried on the property, Steele replied: "There's no reason to believe that, but they (investigators) do want to clear the property to make sure there's nothing else."
Steele said investigators are going over the property with a "ground penetration radar system."
Weaver has not been charged, but Mathews said Sunday that he is a suspect in the case. It was the first time any law enforcement official has identified him a suspect.
Weaver, 39, told reporters months ago he was a subject in the investigation but denied any involvement in the disappearance.
Police Chief Gordon Huiras said more than one barrel had been found at the site, but the others "contained just dirt and gravel."
Agents had dug several shallow holes Sunday about 50 feet from the shed after specialists went over the property with a thermal-imaging device.
A security fence that police erected around the property has become a makeshift memorial — festooned with flowers, teddy bears, and notes in which people have expressed their grief. Throngs of mourners visited the site over the weekend.
Miranda's mother, Michelle Duffey, was, devastated when she heard the news that the remains found Saturday in a shed behind the house had been identified by dental records as her daughter, her attorney, Linda Beloof, told ABC News.
"She had never given up hope that her daughter would come home safely," Beloof said.
Weaver's attorney, Timothy Lyons, would not comment Sunday. His assistant said they were "getting organized."
Weaver has been jailed since Aug. 13 when he was charged with raping his 19-year-old son's girlfriend. The angry and distraught son told 911 dispatchers on the night of the alleged rape that his father had confessed to killing Ashley and Miranda.
Weaver said Ashley was a friend of his daughter who frequently stayed overnight at their house. He said she had even lived at the home for several months last year while her own father was in jail on charges of sexually abusing her.
Ashley's mother, Lori Pond, has told the Portland Tribune that Weaver was lying when he said her daughter lived with him for several months. Records show the girl's father, Wesley Roettger, did plead no contest to sexual abuse and was sentenced to six years' probation.
Her family last saw her on Jan. 9 eating breakfast with her younger sister before school. Miranda, a friend of Ashley's, disappeared March 8 from the same low-income neighborhood in the woods south of Portland.
Residents had been urging authorities to remove the concrete slab, which Weaver had poured shortly after Miranda's disappearance, even since they found out about his son's allegations.
However, Miranda's mother said through her lawyer that she didn't share other people's frustration with the pace of the investigation.
"She understands that if things are done outside of the law, then potential evidence could be thrown out and that would be a real shame," Beloof said.
Weaver's father is on death row in California for two murders. A raped and murdered woman's body was found buried in his yard in 1982.
Weaver told The Associated Press last month that he took Ashley along with his daughter and his girlfriend on a vacation trip to California last year, and that they stopped at San Quentin Prison to visit his father.